Question

For the second period elements the correct increasing order of first ionisation enthalpy is :
(1) Li < Be < B < C < N < O < F < Ne
(2) Li < B < Be < C < O < N < F < Ne
(3) Li < B < Be < C < N < O < F < Ne
4) Li < Be < B < C < O < N < F < Ne

Answer 1

Answer:

a is correct because li be b c n o f ne is proper arrangment

Answer 2

Li < B < Be < C < O < N < F < Ne

Explanation:

"Stability of an element depends upon its electronic configuration"

• The elements which has fully filled orbitals are more stale than the elements which has half filled orbitals and that are stable than the elements which has partially filled orbitals.
• The electronic configurations of given elements are

• $Li - 1s^2 2s^1$      

• $Be - 1s^2 2s^2$        
• $B - 1s^2 2s^2 2p^1$      
• $C-1s^2 2s^2 2p^2$      
• $N-1s^2 2s^2 2p^3$    
• $O-1s^2 2s^2 2p^4$    
• $F-1s^2 2s^2 2p^5$      

• $Ne-1s^2 2s^2 2p^6$  
• Therefore the correct increasing order of first ionisation enthalpy of given species is Li < B < Be < C < O < N < F < Ne